The present invention relates to the removal or reduction of the nitrite and/or nitrate content in water.
The nitrite and/or nitrate contents found in ground and surface water in the Federal Republic of Germany have increased greatly in recent years. They vary considerably depending on location and may in places exceed the maximum acceptable levels. For drinking water, in the newest EEC regulations, a permissible limit value of 50 mg nitrate/1 is recommended, and a limit value of 0.1 mg/1 for nitrite. The increasing nitrate and nitrite contents in much ground and surface water make processes for removing nitrites and nitrates increasingly necessary in the treatment of drinking water.
The principal techniques available for removing nitrites and nitrates from drinking water are biological processes and physical/chemical measures in the field of water desalination. In biological de-nitrification, bacteria are used which in the absence of oxygen process nitrite and nitrate as a terminal hydrogen acceptor. The disadvantage of this process is the risk of contaminating the drinking water with bacteria or their metabolic products, so that subsequent cleaning of the water treated in this way is necessary. In physical salt separation, the problem is simply shifted elsewhere, as nitrite-rich and/or nitrate-rich waste waters are obtained which then have to be disposed of themselves. Accordingly, the removal of nitrites and/or nitrates from water has hitherto involved relatively high costs.